The Xbox Engineering Team Blog gives an inside look at the development of the Netflix application for the Xbox 360. The article includes a rare look at how Microsoft approached the rebuffering problem when the bandwidth rate changed:
- We have switched to using Netflix’s new, more advanced VC-1 encodings when available. The VC-1 streams are much more efficient than their visually-comparable WMV9 counterparts. This allows us to better utilize available bandwidth by buffering more of the feature in less time.
- We have implemented something we are calling “Seamless Stream Switching.” In the past, a starvation meant having to wait while the app rebuffered a new stream. Now, we have the ability to detect a dip in bandwidth that would cause a starvation, and react before we actually starve. Instead of forcing you to wait while the speed test and buffering is redone, we can prepare the new stream behind the scenes while playing out the old one. See the next section for details on how it all works.
- Courtesy of Seamless Stream Switching, you can now switch up to a higher quality stream. Previously, you would always be locked in to the lower bitrate stream if your bandwidth had degraded during playback. Now, if your bandwidth improves sufficiently, your content bitrate could be upgraded as well.
They also have some tips on how to improve playback:
Since you now know some details of how our streaming system works, there are a couple of things you can do to potentially make the system work better for you.
First off, if you absolutely hate Mostly Seamless Stream Switching, you can prevent us from using it by watching all your content in Party Mode. This works whether you watch by yourself or with others. All you have to do is start a Netflix party. If you choose to do this and don’t want to see your Avatar, then use the On-Screen display and use Display Mode to switch.
Secondly, if you have a spiky or otherwise unstable Internet connection, the Pause button is your best friend. Remember how I mentioned that the client will only consider switching down if 1) the buffer falls below a certain threshold, and 2) the buffer level had been decreasing over the last few seconds? Well, when playback is paused, we will continue to read data from the network, but the buffer can’t decrease since playback has been halted. Therefore, hitting the pause button right after playback starts and leaving the content paused for a short while (30 seconds, a minute or two, see what works best for you) is a cheap and easy way to force the buffer level to increase and potentially avoid a downward switch to a lower bitrate stream.
If you use the Netflix app on the Xbox 360 the article is a must-read.
Thanks to Richard for sending this in.